1. Field of the Invention
This invention relates to a method of producing a novel carbon source for fermentation, and also to provide a very inexpensive source of fructose which is economically comparable to sucrose.
2. Description of the Prior Art
Fructose has a comfortable sweetness, and it is about 1.5 - 2 times as sweet as sucrose. There have been known many manufacturing processes for fructose, however, the manufacturing cost is too expensive and accordingly its market is restricted to such special uses as for foods for diabetics.
Sucrose is widely employed as a raw material for the production of fructose. However, it is difficult to treat the mother liquor after the fructose has been recovered. Many methods of treating the mother liquor have been investigated, for example, treating with glucose isomerase, but so far no economically satisfactory process has been developed.
It has been reported in U.S. Pat. No. 3,793,146 that fructose is recovered from a sucrose hydrolyzate in the form of an addition product with calcium chloride and the mother liquor is used as a main carbon source for fermentation of citric acid. However, the fructose produced by the method described in that U.S. patent is expensive because in the calcium chloride method, the sucrose must be pure. Furthermore, the kind of fermentation is limited because a large quantity of calcium ions and chloride ions remain in the mother liquor and inhibit the fermentation.